Ellipsograph



A. iTC'JSSEL Aug. 13, 1929.

ELLIPSOGRAPH Filed Sept. 17, 1928 INVENTOR ,e THU/2 ST BY fi O-SSEL' W. ATTORNEYS Patented Aug. 13, 1929.

UNITED STATES PATENT OFFICE.

ARTHUR s'rossnn, or LAKE WALES, FLORIDA.

ELLIPSOGRAPH.

Application filed September 17, 1928, Serial No. 306,345, and in Germany August 13, 1927.

My invention relates to ellipsographs and has for its object to provide a simple, readily adjustable, and positively operating instrument of this class. The accompanying drawings illustrate two examples of my invention as embodied in-an ellipsograph of the type comprising two stationary pins the points or extremities of which are placed at the foci of the ellipse to be drawn, while the pencil or other marker is carried by a third arm adapted to be given a complete revolution about an axis formed by an extension of the stationary member of the instrument, said axis being perpendicular to the plane of the paper or other surface on which the ellipse is to be drawn. The arm carrying the marker is provided with a marker-holder moving in a plane parallel to that of the paper or equivalent surface.

In prior devices of this class the markercarrying arm was simply arranged to swing about an axis constituted by a portion of the stationary member, but was not movable lengthwise of such axis, that is to say, toward or from the plane of the paper or like drawing surface. In the new instruments illustrated by the accompanying drawings, the marker-carrying arm not only swings relatively to the stationary member, but is adapted to slide relatively thereto lengthwise of the axis of such swinging movement, toward and from the surface on which the ellipse is to be drawn, that is to say, up or down when said surface is horizontal, as is generally the case. This facilitates handling of the instrument, and particularly bringing the marker point in contact with the paper or other surface, as such contact will be effected simply by the weight of the swinging member when released. Preferably, that portion of the swinging member which is guided for sliding along the stationary memher, is located adjacent to a knob or the like forming a handle for such stationary member, so that the user of the instrument may hold and manipulate with the same hand, without changing the position of said hand, both said knob and the guide portion or handle of the swinging member.

In the accompanying drawings, Fig. 1 is a front elevation of an ellipsograph constructed according to my invention; Fig. 2 is a diagrammatic section on line 22 of Fig. 1, with parts omitted; Figs. 3 and 4 are e e ati n takenin directions atr gh angles to each other and showing, upon an enlarged scale, details of the marker and associated parts, and Fig. 5 is a partial vertical section illustrating another embodiment of my invention.

In the construction shown in Figs. 1 to 4, the stationary member of the instrument comprises the two pins 1 and 2, while the swinging member has a body or arm indicated at 3. The pins 1, 2 are provided with points 4, 5 respectively adapted to be driven into or through the paper P or other surface on which the ellipse is to be drawn, it being understood that these points will be located at the foci of such ellipse. In Fig. 2, an ellipse is indicated at E.

In order that the instrument may be adjusted to different major axes of the ellipse (the major axis being defined as the distance between the two foci), the distance between the two pins 1, 2 is made variable. An example of a construction suitable for this purpose is shown in Fig. 1, where the pins 1, 2 are secured rigidly to slides 6, 7 respectively movable along a guide rod 8 which is parallel to the surface on which the ellipse is to be drawn, and specifically, parallel to the major axis of the ellipse. The slides 6, 7 may be locked in their adjusted position, by means of any suitable devices, for instance set screws 6', 7 respectively. At its center, the guide rod 8 has secured to it rigidly a post 9 extending perpendicularly to the plane of the paper and constituting at the same time the pivot or fulcrum about which the arm or body 3 of the movable member is adapted to swing. For this purpose, said arm or body 3 is made with a sleeve 10 mounted to turn on the outer portion of the post 9, between a knob or head 11 located at the free end of said post and a collar or stop 12 adapted to engage the sleeve 10 on the opposite side. It will be noted that the length of the sleeve 10 is considerably smaller than the distance between the knob 11 and the collar 12, so that the said sleeve and the body or arm 3 (with the parts carried thereby, as described hereinafter) may be moved along the post 9, in a direction toward or from the paper P. In order to obtain a better guidance of the slides 6, 7, and to keep them at all times equidistant from the central post 9, I have connected them pivotally with the distant ends of o erg o s or bars 1 14 re Eli spectively, the other ends of which have similar connections with a sleeve 15 mounted to slide freely on that portion of the post 9 which lies between the guide 8 and the stop collar 12. It will be obvious that upon loosening the set screws 6, 7 the draftsman, by moving the sleeve 15 along the post 9, will adjust the two slides 6, 7 equally toward or from each other, so that at all times each of the slides 6, 7 will be at the same distance from the central post 9' as the other slide of this pair. After adjustment, the slides 6, 7 will be locked again, as by the set screws 7'- The body or arm 3 is shown as provided with a guide or sleeve 16' in which a rod 17 is slidable; rotation of this rod relatively to the guide 16' is prevented in any suitable manner, for instance by a pin 17 projec ing from said rod into a corresponding slot 16 of the sleeve. The rod 17 is slidabie horizontally, that is to say, in a plane parallel to the surface of the paper P or other material on which the ellipse is to be drawn. At one side of the guide 16 the rod 17 is surrounded by a coil spring 18 one end of which bears against said guide, and the other against a head 19 at the free or outer end of said rod. This spring tends to press the rod 17 outwardly, that is to say, away from the center post 9. At its inner end, the rod 17 carries a head 20 with a holder 21 for the pencil or other marker 21.

A flexible member, such as a cord 22, is placed in contact with the pins 1, 2 and the marker holder 21, engaging each of them exteriorl'y as shown best in Fig. 2', the outward pressure of the spring 19 keeping the string or cord taut. To guide the flexible member 22 and keep it at the proper distance from the points 4, 5, and 21, suitable formations, such as the external circumferential grooies shown, are provided on the pins 1, 2 and'the; holder 21 at the same level, or in other words, at the same distance from the free or lower ends of said points 4;, 5, and 21. Preferably, each of the three guide grooves is of the same diameter. The flexible member 22 illustrated has two ends, one of which passes from tlie'holder 21 on one side thereof and is tl'ien fastened to a pin 23 adjacent to the guide groove. The other end of said flexible member is shown as passing from the holder on the opposite side thereof, into contact with a guide pin 24 where such end of the member 22 forms a bend as shown in Fig. 3, to then pass to a rotary pin or spool 25 journaled on the head 20. Accidental rotation of this member 25 is prevented either simply its frictional engagement with the head 20, or by any other wellk'liow'n or suitable holding device, such as pawl-and-ratehe't mechanism (not shown). It will be understood that according as a greater or smaller portion of the one end of the member 22 is wound on the pin or spool 25 (which may be rotated by hand, a milled head being clearly shown in Fig. l), the length of that portion of the string or other flexible member 22 which is effective in the drawing of the ellipse (see Fig. 2) may be varied, according to the nature of the ellipse to be drawn in each individual case.

Instead of employing a flexible member 22 having separate ends as just described, I might, without altering the construction of the other parts of the instrument, use an endless string, in which case a looped portion of the flexible member would have both of its runs wound on the rotary pin or spool 25, to enable the effective length of the said menrber 22 to be varied by rotating the spool 25 in one direction or the other, in the same manner as described above. This endless string or flexible member would be engaged with the guide grooves of the pins 1, 2 and holder 21 in substantially the same manner as set forth for a flexible member having separate ends.

The weight of the swinging arm 3 and of the parts moving in unison therewith will normally keep the marker 21 in contact with the paper P. By sliding the arm 3 lengthwise of the post 9, toward the outer end thereof, the marker 21 will be lifted ofif the paper when desired, and the proximity of the sleeve 10 to the knob 11 facilitates this operation or manipulation.

Fig. '5 illustrates another construction for adjusting the distance between the two pins 1, 2 and their points 4:, 5. Instead of the stationary guide rod 8 of Fig. 1, Fig. 5 shows a horizontal spindle 8 journaled in the central post 9 in sucha manner as to hold the spindle against longitudinal movement relatively to said post. The spindle has two screw-threaded portions 8 of'equal but oppositely-directed pitch (left-hand and righthand respectively) in engagement with corresponding internal threads on the slides 6 and 7 which carry the pins '1, 2 respectively. The spindle 8' may be operated by means of a head or hand wheel 8 and locked against accidental motion (after the adjustment has been effected) in any suitable mannor, for instance by a set screw 8 The slides 6 7 are kept in any suitablemanner from turning with the spindle 8 for instance by placing such slides in engagement with guides 9 rigid with the central post 9. It will be noted that this mechanism also provides for the simultaneous equal adjustment of the two slides toward or from the central axis of the instrument, defined by the post 9. The showing in Fig. 5 is fragmentary, it being understood that the parts not illustrated therein may be of the same construction as those of Figs. 1, 2, 8, and 4.

Other means might be employed for adjusting the slides, and I desire it to be understood that various modifications may be made without departing from the nature of my invention as set forth in the appended claims.

I claim 1. An ellipsograph comprising a stationary member having two pins adapted to be positioned at the foci of the ellipse to be described, and a central post provided with a knob and a stop at a distance from said knob, a sleeve mounted to turn on said post and also slidable lengthwise thereof between said knob and said stop, a swinging arm fixed to and movable in unison with said sleeve, a marker-carrying holder connected with said arm for movement toward and away from the axis of the central post, and

2. An ellipsograph comprising an inverted T-shaped frame, a pair of sleeves mounted on the horizontal arms of the T-member, a third sleeve slidably mounted on the vertical arm of the T-member, a link connecting each of the first mentioned sleeves with said third sleeve, means associated with at least one of said sleeves to lock it againstsliding movement, a pair of pins projecting downwardly from said pair of sleeves respectively to establish the foci of the ellipse to be drawn, and means cooperating with said T-frame and said pins to draw an ellipse about the established foci, said means including an elongated flexible means passing around and in slidable engagement with said pins.

In testimony whereof I have hereunto set my hand.

ARTHUR STCSSEL. 

